26   8 A data book gave the following information. H2(g) + ½O2(g) → H2O(l) ΔH d = –285.8 kJ mol–1 (a) State the two conditions denoted by the standard symbol d for this reaction. (2) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (b) (i) Draw a Hess’s Law cycle that would enable you to use the data provided to calculate the enthalpy change of formation of gaseous water, ΔrH. (2) H2(g) + ½O2(g) → H2O(g) Data: H2(g) + ½O2(g) → H2O(l) ΔH 1 d = –285.8 kJ mol–1 H2O(l) → H2O(g) ΔH 2 d = +2.261 kJ g–1 27   (ii) Calculate the enthalpy change for the reaction shown. H2(g) + ½O2(g) → H2O(g) (3) (Total for Question 8 = 7 marks) TOTAL FOR PAPER = 80 MARKS 28  